Last week was a tough time to turn bearish. Since hitting a bottom on Tuesday, the Dow Jones Industrial Average has jumped by 11% in less than two weeks, raising hopes among some investors that the U.S. and Europe may be able to power through their summertime woes.

Not for Jeff Applegate.

Mr. Applegate, the 61-year-old chief investment officer of Morgan Stanley Smith Barney, last week made his biggest bearish shift in more than two years, battening down the hatches and reducing his exposure to stocks, high-yield bonds, commodities and real-estate investment trusts.

Mr. Applegate argues that the world is heading into recession, hurt by political paralysis that has added uncertainty while withholding stimulus at a time of weakness. And the past few days’ rally, fueled by progress on a European bailout and an encouraging U.S. jobs number, has done little to change his mind.

“We’re seeing a relief rally in global equities in recent days, but at the end of the day, we think if Europe is heading into recession — which I think they are — and if the U.S. is heading into recession — which I think we are — then there’s more downside in equities,” Mr. Applegate said.

After a strong start to the year, U.S. stocks wavered in the summer as Europe’s debt crisis intensified. Stocks tumbled further in August as the worries spread to the U.S. economy, sending the Dow to a one-year low last week. But as the economic data showed tepid signs of improvement, a number of investors and traders have begun to argue that the stock-market may have turned a corner.

Mr. Applegate said the Global Investment Committee he runs at MSSB, which meets as many as 20 times a week but makes only very infrequent changes to its positioning, didn’t come to the conclusion lightly.

Two and a half years ago, Mr. Applegate began shifting to a more aggressive position, benefiting from the major U.S. stock indexes’ 70% increase off its the March 2009 trough. While he says there was “no single event” that tipped the balance this time around, Mr. Applegate’s pessimism is based on well-known concerns: the ongoing debt crisis in Europe, fears of a “double dip” recession in the U.S. and concerns about central bankers’ ability to support the wavering global economy.

“The policy action being taken, both in Europe and the U.S., is too little, too late,” he says.

Mr. Applegate doesn’t rule out a comprehensive plan to prevent a European banking crisis, but he worries that Europe’s economy may nonetheless falter — particularly as the European Central Bank holds interest rates steady after several increases earlier this year.

“Europe will avoid a Greek default, but what we ware saying is that they’re heading into recession anyway,” he said. “The European economy wasn’t exactly robust to begin with, and it’s hard to see how it’s going to get better.”

To be sure, Mr. Applegate concedes that the economic picture could gradually improve, “in which case our call is going to be incorrect.”

“We’re sifting through the evidence all the time, so if it looks like we’ve got it wrong, we’ll need to change our course,” he said.

“We have always said that we never try to time the market, and we don’t,” he said, adding that his committee is flexible enough to reverse course — or even turn more bearish if economic conditions deteriorate more than he fears. “We could still get more defensive,” he said.

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